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Ecology and salmon related articles

Salmon-eating Terns Solve Problem Themselves

by Jonathan Nelson, Correspondent
The Oregonian, May 14, 2000

The birds forsake a Columbia River island
from which Army engineers planned to chase them

The U.S. Army Corps of Engineers' plan to chase thousands of salmon-eating Caspian terns from a man-made island in the Columbia River was blocked earlier this spring when a federal court judge ruled that the protected birds could not be disturbed.

Now it appears that the terns didn't need to be frightened away. They are shunning the island on their own.

The seabirds have abandoned the island where they have nested since 1986 by an 8-to-1 ratio, preferring to nest where the corps wanted them to -- on a similar island closer to the river's mouth.

The latest count taken in early May shows that almost 16,000 terns are nesting on East Sand Island, located five miles from the ocean, compared with approximately 2,000 birds on Rice Island, which sits 22 miles up the river. Last year, early migration numbers showed 11,400 birds choosing Rice Island and 1,700 terns nesting on East Sand Island.

The location of nests has become increasingly controversial. The terns typically feast on young salmon trying to reach the sea. The National Marine Fisheries Service, which ordered the corps to remove the terns, says the birds consumed about 10.8 million young salmon and steelhead last year, or about 11 percent of the 95 million smolts that left the Columbia. Scientists believe that if the terns nest closer to the ocean on East Sand Island, they will dine on other species in addition to salmon and steelhead.

But the effort to relocate the terns ran into trouble. The terns -- like the salmon -- are a protected species.

Last year, a multiagency organization called the Caspian Tern Working Group attempted to move the terns from Rice to East Sand Island with little success. The group reduced the amount of nesting space on Rice Island and tried to create an inviting habitat on East Sand Island by clearing grass, planting tern decoys and playing tern calls through speakers.

This year's turnaround comes with little human intervention, said Dave Craig, a research associate at Oregon State University who is studying the tern colony. Craig said a four-acre section of East Sand Island was cleared to produce the sandy surface terns need to reproduce. Decoys and speakers playing tern calls were again used.

On Rice Island, nature took over by creating a carpet of wild weeds and summer wheat that covers the area where terns once nested. The few terns that have returned to Rice Island are becoming prey for bald eagles. Craig said gulls are raiding the nests so frequently 100 eggs a day are lost.

"There is lots of natural phenomena making Rice Island less attractive than last year."

The corps intended to use humans this year to scare the terns off Rice Island, but at the last minute the National Audubon Society, Defenders of Wildlife, the Seattle Audubon Society and the American Bird Conservancy filed a lawsuit alleging there is no firm evidence relocation would help salmon and that there is too little information on how relocation could affect the terns. A federal judge in Seattle agreed and halted the corps' plans.

Related Sites:

Jonathan Nelson
Salmon-eating Terns Solve Problem Themselves
Spokesman Review, May 14, 2000

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